Skimmer mechanism for a waste flotation cell

ABSTRACT

A skimmer blade is utilized to gather scum from the surface of a tank and convey same up a ramp into a collection trough. The blade is preferably mounted on two flexible members attached to a driven support arm for this purpose. The flexibility, length and cross-section of the blade supporting members can be chosen for proper depth of entry into the floating material and proper contact with the ramp.

United States Patent [191 Peterson June 26, 1973 SKIMMER MECHANISM FOR A WASTE FLOTATION CELL [75] Inventor: Ronald L. Peterson, Richmond, Va.

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

[22] Filed: Mar. 19, 1971 [21] Appl. No.: 126,190

[52] US. Cl. 210/525, 210/528 [51] Int. Cl B01d 21/06 [58] Field of Search 210/528, 525

[5 6] References Cited UNITED STATES PATENTS 3,465,887 9/1969 Cookney 210/525 Primary Examiner-Samih N. Zahama Assistant Examiner-F. F. Calvetti Attorney-A. T. Stratton, Z. L. Dermer and M. B. L.

l-lepps [57] ABSTRACT A skimmer blade is utilized to gather scum from the surface of a tank and convey same up a ramp into a collection trough. The blade is preferably mounted on two flexible members attached to a driven support arm for this purpose. The flexibility, length and cross-section of the blade supporting members can be chosen for proper depth of entry into the floating material and proper contact with the ramp.

5 Claims, 3 Drawing Figures SKIMMER MECHANISM FOR A WASTE FLOTATION CELL BACKGROUND OF THE INVENTION a vertical centrally mounted shaft connected to a horizontal arm on which are mounted skimmer blades. As the vertical shaft rotates, the skimmer blades move around the surface of the tank collecting floating material. The blades then pull the collected material up a ramp into a collection trough.

The skimmer blade assembly must accordingly be designed for proper depth of entry into the floating material and for proper contact with the ramp as the skimmer blade is moved up the ramp and over the trough. I-Ieretofore, this has been accomplished by an assembly including multiple hinges or a hinge and roller mechanism for the supporting arms of the skimmer blade. Because of the geometry of round tanks and the requirement for moving the skimmer blade up and across a trough, the skimmer mechanism must be designed to provide freedom of movement at least two mutually perpendicular planes, that is, the skimmer blade mounting member must be so constructed as to allow the skimmer blade to be moved vertically upward and downward as the blade traverses the ramp and trough arrangement. Also, inasmuch as forces on the skimmer blade cause same to twistor rotate while moving up the ramp, the mounting member must also be capable of permitting and controlling this motion.

SUMMARY OF THE INVENTION The relatively complex skimmer support structure I the length and cross section ofv these members, as well as the proper choice of flexibility of the material from which the support members are made and the weight of the skimmer blade, the depth of penetration of the blade into the frothy foam formed on the top of the flotation cell as well as the desired contact with the up ramp of the scum trough can readily be controlled. The flexible support members will allow the skimmer blade to sag down under its own weight into the floating material. While moving up the ramp, these members will flex upwardly allowing the blade to closely contact the ramp throughout its travel. Bars may be provided across the trough and down the return side to support the skimmer as it moves across the rough and to allow the skimmer blade to move smoothly down into the floating material to resume its collection run.

The connection of the flexible support members to the driven support arm can be made adjustable so that the length of the flexible support members can be varied to vary the depth of sag and the freedom of upward and twisting motion of the skimmer blade. Such an adjustment may be desirable, as for example, where the froath is thicker than usual for a period of time.

DESCRIPTION OF THE DRAWINGS A better understanding of the invention may be had with reference to the accompanying illustrative embodiment of the invention, in which:

FIG. 1 shows an isometric view of the skimmer mechanism in accordance with this invention;

FIG. 2 shows a side view of same; and

FIG. 3 is a plan view of a treatment tank utilizing the skimmer mechanism of FIGS. 1 and 2.

DESCRIPTION OF A'PREFERRED EMBODIMENT Referring to FIG. 3, there can be seen a tank 10 including a scum trough l2 and a skimmer mechanism 14. The tank 10 may. include apparatus, for example, for producing a flotation of particles which are carried in a liquid medium. As is well known in the art, minute gas bubbles can be produced proximate the bottom of tank 10 which will attach themselves to the particles in the liquid medium and cause these particles to find their way to the surface of tank 10 in the form of a frothy foam. The bubbles may be produced within a well 15 at the bottomof the tank 10. The tank 10 depicted includes'a scrapper assembly 11 comprising a driven support arm 13' and a plurality of scrapper blades 17. Any particles which settle to the bottom of the tank 10 are moved inwardly by the blades 17 to a collection drain '19. The particles are conveyed from the drain 19 through an outlet pipe 21. The arm 13 is connected to a vertical central shaft 16 driven by a motor 23 mounted on a walkway 25.

In the embodiment shown, i.e., round tank, the skimmer mechanism I4 for floating particles, may also be mounted on the shaft 16'. A support arm 18 is mounted I on the driven central shaft 16 and extends outwardly therefrom and over the scum trough 12.

The scum trough 12 consists of an open chamber 20 having vertically mounted side walls 22 and 24, a front wall 26, which is preferably a portion of a circular wall 28 which partially surrounds the central shaft 16, and a downward sloping bottom wall 30. The downward sloping bottom wall 30 causes the particles which settle in the scum trough 12 to migrate towards an outlet line 32. The scum trough 12 further includes an up ramp 34 along which the froth containing particles can be conveyed from the top of the tank 10 into the scum trough l2, and cross-members 36 which act to direct a skimmer blade 41 into the foam on the far side of the scum trough 12. The cross-members 36 preferably has its near end attached to the wall 22 of the trough l2 slightly below the top of the up ramp 34-so that any particles adhering to the blade 41 are shaken free.

In accordance with this invention, the skimmer blade 34 is connected to the support arm 18 by means of one or more flexible members 36, the flexible members 36 may be suitably attached to the skimmer blade as by welding or bolting. At the end of the flexible members 36 opposite the skimmer blade, the attachment to the support arm 18 is preferably made adjustable so that the length and therefore the depth of entry of the skimmer blade into the frothy foam can be adjusted. A suitable means for providing adjustability in the length of the flexible support arms 36 with relation to the support arm 18 may comprise two plates 38 and 40 between which a portion of the flexible members 36 is sandwiched. These plates may have aligned openings 37 through which U-shaped members 42 can protrude, which members 42 are threaded on their outward ends where desired. In any case, an inexpensive, highly controllable skimmer support mechanism is provided for removing separated particles from the surface of the tank 10.

Therefore, I claim:

1. A skimmer mechanism for conveying a particle filled foam up a ramp into a scum trough comprising,

to receive nuts 42. The nuts 42 can be tightened on the U-shaped members 42 so as to closely support the flexible members 36. Loosening of the nuts 42accordingly allows for the length ofthe flexible members to be adjusted by means of sliding translational movement between the plates 38 and 40.

A feed-blade 39 can also be mounted onthe driven in combination, a vertically oriented skimmer blade. supportedly suspended with a degree of penetration into the foam on the top of a tank, a driven member,

I at least one generally horizontally oriented flexible shaft 16 to move the particle filled foam to the outside 7 of the tank 10 and into the path of the skimmer blade.

41. v r I Accordingly, it can be seen that by proper choice of the material of the flexible members 36, by an adjustment of their length with respect to the support arm 18, and by a proper choice of their cross-section, the degree to which the skimmer blade 41 protrudes into the frothy foam can be adjusted, and the skimmer blade 41 is provided with a simple means by which it can move vertically up the ramp 34 while twisting slightly during its travel thereon. a

Means such as a plurality of bolt holes (not shown) may further be provided, for example, on the surface of the skimmer blade 41 or on the end of the flexible members 36, to receive weighted boltswhich mayact to further adjust thedegree of penetration of the skim member flexible solely in the vertical direction and affixed at one end to the driven member and at the other endto the skimmer blade, said flexible member providing the only means forvertical movementof the blade l v and being formedof a predetermined material, length,

, flexible members being the only means for providing mer blade41 into the frothy foam. Moreover, relatively non-flexible arms 46 provided with stops 48 (see FIG. 2) can be affixed to the supportarm 18 to ,restrictthe degree of penetration of the skimmer blade 41 into the foam by restricting the sag ofthe flexible members 36 the aforedescribed vertical motion.

4. The mechanism of claim' 1 including a curved blade supported on the driven member in the plane of the skimmer blade for conveying foam into the path of the skimmer blade. a 1 i 5.Thernechanism of claim -1 including stop means vertically'spaced from said flexible member to limit vertical flexure thereof. 1

t 1k 1: a: 

1. A skimmer mechanism for conveying a particle filled foam up a ramp into a scum trough comprising, in combination, a vertically oriented skimmer blade supportedly suspended with a degree of penetration into the foam on the top of a tank, a driven member, at least one generally horizontally oriented flexible member flexible solely in the vertical direction and affixed at one end to the driven member and at the other end to the skimmer blade, said flexible member providing the only means for vertical movement of the blade and being formed of a predetermined material, length, and cross-section so as to provide for a predetermined depth of penetration into the foam and vertical movement and twisting for conveying same up the ramp of the scum trough.
 2. The mechanism of claim 1 including means for affixing the flexible members to the driven member, said means being adjustable such that the length of the flexible members between the skimmer blade and the driven member can be varied.
 3. The mechanism of claim 2 including at least two flexible members supporting the skimmer blade, said flexible members being the only means for providing the aforedescribed vertical motion.
 4. The mechanism of claim 1 including a curved blade supported on the driven member in the plane of the skimmer blade for conveying foam into the path of the skimmer blade.
 5. The mechanism of claim 1 including stop means vertically spaced from said flexible member to limit vertical flexure thereof. 